The planned Einstein Telescope consists of three tubes, each 10 kilometers long, at a depth of 200 to 300 meters underground. With laser beams, so-called gravitational waves can be measured there. These are waves in space-time that are created when a massive star explodes. Its existence was predicted about 100 years ago by Albert Einstein. Its existence was confirmed in 2015. By studying gravitational waves, scientists hope to gain more insight into, for example, the origin of the universe and black holes.